I had to replace the outdrive on my 2004 Cobalt 246 with a 5.7 280hp engine, which had a 1:95 ratio DP-S drive. I purchase a used one that was supposed to be the same but actually ended up as a 1:78 ratio. I had F6 props on the original drive and it turned 4800-4900rpm at WOT. I have the F6 on this outdrive and can only get 4000-4100rpm WOT on this drive. Any suggestions as to what F series props i need to get the maximum performance for my boat.
